


The Cure

by WevyrDove



Category: Supernatural, wincestiel - Fandom
Genre: Angel/Demon Sex, Demon!Dean, M/M, PWP, Rape/Non-con Elements, Top!Castiel, Wincestiel - Freeform, alternate ending/deleted scenes in 10x03, angel!cas - Freeform, bottom!Dean, the cure isn't human blood
Language: English
Status: Completed
Published: 2015-03-17
Updated: 2015-03-17
Packaged: 2018-03-18 08:37:54
Rating: Explicit
Warnings: Rape/Non-Con
Chapters: 1
Words: 4,338
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/3563234
Author URL: https://archiveofourown.org/users/WevyrDove/pseuds/WevyrDove
Summary: <blockquote class="userstuff">
              <p>When blood isn't enough to make Dean human again, Castiel tells Sam about another cure. Sam is shocked by what Castiel has to say, but determined to save his brother. Alternate ending to 10x03 Soul Survivor.</p>
            </blockquote>





	The Cure

**Author's Note:**

> I started thinking about demon!dean again when there was a flurry of interest on tumblr on my existing fics. This has been on my queue since the episode aired last fall: my headcanon for 10x03. I'm not sure how i feel about this fic; I was in the mood to write a PWP since it's been awhile. Thanks for reading as always, and if you feel so inclined, please leave feedback! The more you talk to me, the more motivated I will be to write more. 
> 
> Much love,  
> WD

Sam had been running for what seemed like hours, but had actually only been minutes since Dean had escaped the chair. And now Dean was right in front of him, and Sam couldn’t run anymore.

Dean’s eyes flicked black. “Oh Sammy.” He sneered. “You want to save me, but maybe I don’t want to be saved.” He passed the hammer to the other hand.

Sam gasped, cradling his arm that hung uselessly in the sling. “Dean!” he said, backing up but only to meet the cold stone wall. “Don’t do this. Please…” His eyes were wild and fearful.

“Sammy boy.” Dean smirked. “I won’t hurt you…much.”

Dean closed the space between them in two steps, and the swung the hammer. Sam cringed, shutting his eyes tight and bracing himself for the blow. But the hammer only cracked against the wall, startling him. His eyes flew open, and Dean dropped the hammer on the floor. He slammed his hands on the wall on either side of Sam’s neck. Sam flinched and Dean grinned maliciously.

“Look at you, baby brother.” Dean said contemptuously. “So helpless and afraid. Who’s gonna help you now?”

“Don’t do it, Dean.” Sam tried again. He felt adrenaline rushing through his body, and he was wondering if he could just barrel through Dean, catch him off guard enough to escape. Dean noticed his body tensing.

“Don’t try to run, Sammy.” Dean chided, his eyes narrowing. “You know I’ll catch up to you. I’m stronger, I’m faster, and I’m a demon.”

“Dean, what do you want? I’m more useful to you alive.” Sam said desperately. “I’ll help you, I’ll do anything.”

“Anything?” Dean smiled, his black eyes glittering. “And who said anything about killing you?”

“I-“ Sam started to say. “What do you want?”

“Oh not much.” Dean said lightly, plucking at Sam’s shirt. He pulled out a knife from his waistband. He pressed the tip against Sam’s chin.

“Please Dean…” Sam begged, but Dean just increased the pressure on the knife, so the skin broke and blood welled over the tip of the blade. Dean smiled and pulled the knife away, licking away the blood as Sam watched in horror.

“You taste so good, Sammy.” Dean praised.

Sam whimpered. This wasn’t Dean. This was the Mark and the demon talking. But at the same time, it was Dean- he wasn’t possessed. He had died and come back as this…this abomination. Sam thought of Castiel, how he was glad that Castiel wasn’t here to see Dean this way. Castiel couldn’t help them now, his grace was almost gone. Sam remembered how weak he had sounded on the phone; he wouldn’t get here on time. Dean lifted the knife and ran it lightly down Sam’s chin and neck. Sam shuddered, waiting for Dean to cut him again. Instead, Dean used the knife to slice through the buttons on Sam’s shirt and expose his chest. Dean opened the ruined shirt to expose the anti-possession tattoo on Sam’s left shoulder. 

“Too bad these are useless if you’re gonna get possessed the way I’m gonna do ya, Sammy.” Dean laughed. He tugged at Sam’s belt and sliced it with the knife. To Sam’s shock, Dean tugged at his waistband and sliced the button on the fly of his jeans. He ripped Sam’s jeans apart, and tugged them down roughly, so they pooled at Sam’s ankles. Sam was down to his briefs. Dean ran the blade along the bulge in Sam’s underwear. His other hand pinned Sam’s good arm down when Sam tried to cover himself

“Don’t, Dean.” Sam whined. Dean would never do this. If they ever got Dean back, he would be horrified at what he had done to Sam. He was pleaded as much for his own sake as his brother’s.

“Oh Sam, you don’t need to pretend anymore.” Dean said lasciviously, his eyes roaming up and down his brother’s half naked body. “I know what you want.”

“No, Dean.” Sam sobbed. “I don’t. You aren’t yourself. I’m your brother!”

“Hmm, you think that I didn’t want this before I became what I am?” Dean released Sam’s arm and grabbed the band of Sam’s briefs. He let the knife cut through the cloth, exposing his brother. “I pushed those feelings down because of human conventions. Now that I’m a demon, I realize those boundaries are meaningless.”

Sam gulped. Dean was looking at him like he was going to eat him alive. “No…” Sam protested weakly. Despite himself, he felt a surge of desire.

“Your mind says no but your body say yes.” Dean growled, pressing his thigh against Sam’s growing erection. Sam whimpered. “Did you know that I watched you once?” Sam’s eyes widened and Dean laughed.

“Yeah, I had come home and you didn’t hear me. I was looking for you and saw you in your room; the door was partially open and I saw you on your bed, jacking your cock.” Dean smirked at the look of shame that came over Sam’s features. He kept moving his thigh against Sam’s cock. “Your eyes were closed so you didn’t see me. I watched you come all over yourself, and heard you say my name. Fuck, I tried so hard to get that image out of my head but it always stayed with me. And it always came up when I was getting myself off. What a waste of effort that was. We could have been fucking regularly. No one would have ever had to know.”

Sam was trying his best not to react, but his cock betrayed him. His breath hitched as Dean ground down with his thigh. “N-no, Dean…please…” Sam begged once more.

“Come on, Sammy. Not the first time you fucked a demon. Now a demon is gonna fuck you.” Dean moved his leg and gripped his brother with his hand. Sam automatically bucked into his grasp. “Good boy.”

“No…” Sam whispered.

Tears leaked from Sam’s eyes. He was defeated and Dean knew it. Still, he had to try. He tensed under Dean’s touch and then he lunged, trying to pull out of Dean’s grasp. Dean was so much stronger though, and Sam was exhausted; Dean easily held him down. He pressed the knife against Sam’s neck, pushing just enough to draw a line of blood.

“I’ll tie you up if I have to Sammy.” Dean sneered. Sam was crying openly now, and he couldn’t hold back the whimpers that escaped from his lips. Dean removed the knife and tucked it back into his waistband. He bent his head to lick the line of blood that welled from the cut on Sam’s neck. Sam couldn’t help moaning. “You like this, Sammy. I knew it.” He smirked and reached down to cup Sam’s cock. “You’re so fucking hard for me.”

“Dean…this isn’t you.” Sam sobbed. Dean leaned in to kiss the tears off Sam’s face. Sam flinched and looked surprised.

“I bet you thought the salt would hurt me.” Dean grinned maliciously. “Not when it’s human tears. Demons feed on pain.” Dean licked his lips deliberately. “Your tears taste so fucking good to me.” Dean moved down to Sam’s neck again, licking along the seam of the cut.

Sam closed his eyes. Dean gripped his cock hard and he moaned. Dean stroked up and down and Sam bucked into his grasp again. Dean thumbed the head of his cock and Sam whimpered.

“Don’t fight it, Sammy.” Dean rasped in his ear. “I’m gonna make you feel so good, baby brother.”

Sam kept his eyes closed, feeling shame and disgust at himself as Dean continued to work him. At the same time, it felt good and he just wanted to cum. Sam panted as his body tensed and reached for the peak. Dean pulled his hand away and Sam gasped, his eyes flying open.

“Beg for it.” Dean growled. Dean had the knife in his hand again.

Sam just looked at Dean desperately, his eyes wide and tearful. His cock was leaking and aching for release. He reached down to touch himself, thinking it the lesser of the two evils – after all, Dean had already watched him once. Dean shoved Sam’s hand away, pinning it down easily. He pressed the flat of the blade against Sam’s length, and Sam sucked in a sharp breath at the feel of the cold metal, his whole body stilling.

“Naughty boy.” Dean said, shaking his head. “You’re only coming when I let you, not before.”

Sam was holding his breath, afraid to move when the knife was against his cock. Dean slid the knife up slowly, letting it drag against the tip of Sam’s cock. Sam squeezed his eyes shut. When Dean pulled the knife away, Sam opened his eyes again. Dean lifted the knife to his own lips and licked the smear of precum that coated the blade. Sam couldn’t help hitching his breath at the sight.

“Turn around.” Dean ordered, still holding the knife.

Sam turned around so he was facing the wall and then Dean slammed him against it, making him cry out in pain as his broken arm was crushed between his body and the concrete. Sam whined when Dean palmed his ass. He could hear Dean’s ragged breathing behind him as he massaged Sam’s buttocks. He heard the slide of the belt buckle and then the ping when it dropped to the floor. A rustle of cloth and he knew Dean and dropped his pants. He felt Dean’s hot, hard length pressing against his ass and he couldn’t help but whimper again and press back in response.

“Don’t do this…” Sam whispered weakly.

Dean just laughed. He slammed Sam against the wall again, and his brother yelped at the pain in his bad arm. “You’re lucky I don’t just fuck you dry.”

Sam heard Dean spit into his hand and slick up his own cock. Dean pushed Sam’s thighs apart roughly, and then he was lining himself up with Sam’s entrance. Sam leaned his forehead against the wall, trying not to think about what was happening. He felt the head of Dean’s cock nudging against his opening and it felt impossibly huge. He braced himself for the rough entry but it never happened. In the next moment, Dean was snarling and being pulled away from Sam. Sam turned around and saw Castiel, his eyes blazing blue and holding Dean tightly from behind with his arms.

“It’s over.” Castiel growled. He tightened his grip on Dean as he howled in frustration and tried to break Castiel’s hold. “It’s over, Dean.”

Sam could only watched as the demon and angel struggled. Castiel never broke his hold, despite Dean’s best efforts, and finally the demon collapsed.

“It’s over.” Castiel stated, his eyes returning to their normal blue. He let Dean fall to the floor and went over to Sam who had sagged down to the floor. “Are you ok, Sam?” Castiel examined Sam with concern, noting the cut on his neck and the puncture in his chin.

Sam was too distraught to be embarrassed by his nakedness as Castiel ran his hands over his body. He felt like crying again seeing the worry in Castiel’s eyes. “I-I’m ok, Cas. Really. I’ll be ok.” Sam took a deep breath, feeling shaky.

“I came just in time.” Castiel nodded. “I am sorry I couldn’t get here sooner.”

“It’s ok, Cas.” Sam said, sucking in a breath and when Castiel palpated his broken arm.

Castiel held Sam’s hand and put his other hand on the arm. The angel’s eyes glowed with grace and Sam felt a warm and tingling sensation. His arm stopped aching; he tried moving it and found that Castiel had reknit the broken bone. Castiel cupped Sam’s cheek and sealed the cuts on his chin and neck as well.

“How?” Sam asked. “You got your grace back…I saw your eyes…you just healed me…”

“Long story. Crowley, stolen grace.” Castiel said dismissively. He glanced back at Dean who was still unconscious and lying on the floor. “We need to act quickly if we are to cure him.”

“The blood didn’t work, Cas.” Sam said, defeat in his voice. “What can we do?”

Castiel held Sam’s eyes. “There is another way. But you won’t like it.”

“What is it?” Sam asked. “Tell me. I’ll do anything to save Dean.”

Castiel explained it to Sam, and Sam understood why Castiel hadn’t brought it up earlier. He was still shaken but he gathered his resolve.

“Let’s do it.” Sam agreed

Castiel nodded grimly.

…

Dean woke to blinding lights in his eyes. He was strapped to a table and completely naked. There were goose bumps on his skin from the chill air. He recognized that he was in the basement, on an examining table. His legs were bound and raised up in stirrups.

“He’s awake.” Sam murmured. Dean tried to see where his brother’s voice was coming from, but he couldn’t see beyond the lights.

“Ok.” Castiel replied. “Are you certain you can do this, Sam?”

Dean couldn’t hear a response but assumed that Sam had nodded. He heard rustling, and then Castiel appeared in his field of vision. The angel was in his usual suit, but his trenchcoat was missing.

“Cas?” Dean asked in confusion. He tried to move his hands from their bonds but they were secure and tight.

Castiel lips formed a thin line, and his eyes were expressionless. “Just lay still, Dean.”

“What are you doing?” Dean asked, his voice sounding panicked. “I can’t quite remember what happened…the last thing I remember was Sam was giving me the blood.”

Cas didn’t answer but instead grabbed Dean’s hips and slid them down toward the edge of the table. Dean’s arms were raised above his head with the new position, and his knees bent. His legs were spread so he was exposed to Castiel.

“Cas…” Dean tried again. “What’s going on?”

“We’re going to cure you, Dean.” Castiel offered. “Just let us work. It will be ok.”

Before Dean could say anything else, Castiel was unbuckling his pants. Dean’s eyes widened as he watched the angel drop his pants and tug his boxers down, revealing his rigid cock. Castiel pulled a vial out of his pocket and emptied the contents into his palm. He tossed the vial away and then slicked up his hand. Dean started protesting as Castiel pressed a wet finger against his opening. “What the fuck are you-“ Castiel pushed his finger inside and Dean gasped. “Cas!”

“Sam convinced me to prepare you first, so it would be less painful.” Castiel said clinically as he began to push his finger in and out gently.

“This-is-” Dean gritted. “The cure?” He bit back a moan as Castiel continued to move his finger back and forth. Dean barked a laugh. “You’re going to fuck the demon out of me?”

Castiel added a second finger and Dean grunted as the angel’s fingers pumped in and out. Castiel looked at him impassively. “Actually I will be filling you with my grace.”

Dean snickered. “Angel cum? Seriously?” Suddenly he remembered that Sam was in the room. “Sammy? You ok with this?”

Sam moved into Dean’s vision, standing by his head. “It’s the only way, Dean.” Sam looked ashamed. He had pulled his jeans back up but he still wore the tattered remains of his flannel shirt.

Castiel pressed another finger into Dean and started thrusting harder. Dean pressed back with a groan. “Just fucking do it then.” He gritted.

“There’s another part to the cure.” Castiel continued, still jamming his fingers in and out of Dean’s hole.

Dean squirmed as Castiel fucked him with his hand, but he paused long enough to ask. “What other part?” Castiel paused his motions and glanced at Sam. Dean noticed.

Sam wouldn’t look at his brother. “The cure requires..a human component too.”

“You’re shitting me.” Dean glanced at both of them and laughed harshly. “Gee guys, you could have just asked me if you wanted a threesome.” He tried to catch Sam’s eye but his brother still kept his eyes down. “You’re serious.” Dean choked.

“I’m sorry, Dean.” Sam muttered. He looked over at Castiel. “Let’s just get it over with.”

“Why not enjoy it, Sammy?” Dean sneered. His eyes flicked black. “Remember, I saw you. And I lied, I remember everything. How hard you were and how you were begging for me to fuck you raw. Until this _angel_ showed up and ruined everything.” Dean snarled at Castiel and pulled at his bonds again. Castiel responded by removing his fingers and pulling Dean’s hips hard against him.

“Be silent.” Castiel growled.

The angel gripped his cock, slicking it with lube and then positioned himself against Dean’s entrance. Castiel pressed his hands on Dean’s thighs, keeping the demon spread wide, and then thrust in hard, sheathing himself fully in a single motion. Dean roared in fury as the angel entered him. Castiel groaned and finally his expression broke as he buried himself inside Dean. His features twisted with anguish and need as he started fucking Dean in earnest. Dean hissed and spat as Castiel slammed himself in and out, pressing bruises into Dean’s thighs. Sam stood to the side, watching the angel pounding the demon, and felt himself hardening at the sight. He pressed his palm against his jeans, but he needed to wait for Castiel’s word.

“Cas. You dirty-ah! dirty-oh! angel.” Dean taunted, his words punctuated by moans as Castiel rammed him. “If the others could see you now, how far you’ve fallen.”

Castiel didn’t answer, but his eyes shone with grace as he glared at Dean. Sam wasn’t sure how much longer he could wait- the sight of Castiel ramming himself in and out of Dean was the most obscene and profane thing he had ever witnessed. He reached inside his pants to grab his rigid cock and started stroking himself, his gaze riveted on the unholy joining of angel and demon.

Suddenly, Castiel leveled his blindingly blue gaze at Sam. “Now Sam. I will wait for you.” His voice was steady even though his expression was completely debauched.

Sam slipped his jeans off quickly, and straddled Dean’s chest. He braced himself on his palms, careful not to put his full weight on his brother, leaning forward slightly. Dean smirked at him, his black gaze focusing on Sam’s cock.

“Give it to me, Sammy.” Dean jeered, darting his tongue out. “I can take it. I already had a taste earlier.” He looked past Sam at Castiel. “Who said you could stop fucking me, angel?”

Castiel snarled at Dean from behind Sam but stayed still. Sam ignored Dean, trying not to look at his brother’s face. He had been shocked when Castiel had told him what had to be done, but he was determined. He pressed the head of his cock against Dean’s lips.

“Aren’t you afraid I’m going to bite you?” Dean asked mockingly. “You’re too-“ Dean gagged as Sam slid himself between his brother’s lips, his thick cock hitting the back of Dean’s throat. Sam moaned at the hot wet sensation of Dean’s mouth surrounding him. He felt Dean’s teeth graze his cock as he started easing himself in and out. Dean's words were muffled against Sam’s cock and Sam pulled out to let him speak.

“You’re being too gentle, baby brother. I can take it. Fuck my mouth, Sammy.” Dean leered at Sam, who cringed when he saw Dean ghastly grin. The demon’s mouth was slick and wet, his black eyes shining brighter than usual.

“Shut up.” Sam growled and pushed his cock into Dean’s willing mouth. He closed his eyes and just focused on the feel of the demon’s mouth, trying not to think. He heard Dean’s muffled moans around his cock but he was beyond the point of shame and instead they spurred him on. He gripped the sides of Dean’s head and started slamming himself in and out in earnest. He wouldn’t last much longer, especially with Dean swirling his tongue all over his shaft as he slid in and out. Sam chanced a look back at Castiel. The angel had started fucking Dean again and Sam almost came as he caught a glimpse of Castiel fucking hard into Dean.

“Cas…I can’t hold on much longer.” Sam groaned.

“Then do it.” Castiel panted, not pausing in his thrusting. “I will follow.”

Sam closed his eyes again and drove his cock into Dean’s mouth. A moment later he was falling over the edge and coming hard. “Dean!” He cried out in anguish even as he pounded Dean’s face and filled his brother’s mouth with his cum. He felt Dean swallowing it all. Castiel roared as Sam’s orgasm receded. The angel was shouting words that were foreign to Sam, and he guessed they were Enochian. Sam pulled himself out of Dean’s mouth and turned to look back at Castiel; the angel’s eyes were blazing so brightly that Sam couldn’t look at them. He heard a crack and the sound of fluttering wings, the air in the room swirling with gale force winds. And then Sam heard his brother screaming in what was either agony or pleasure, or a mixture of the two. He felt his brother buck under him and looked into Dean’s eyes. Dean was hissing and spitting, but as Sam watched his features relaxed and his eyes transitioned abruptly to green. The winds in the room disappeared as suddenly as they had risen. Sam hopped off the table.

“Dean!” He framed his brother’s face with his hands. “Dean!” Sam spoke urgently, his face close to Dean’s.

Dean looked dazed and exhausted. Sam thumbed away the spittle at one corner of his brother’s mouth.  Castiel was beside him now. For a moment Dean seemed to stare at them both with shocked recognition, but then his eyes slipped closed and his breathing deepened.

“Let him sleep.” Castiel said, pulling Sam away gently.

“I need to unbind him and cover him.” Sam protested.

“Ok, Sam.” Castiel nodded. “But we have to keep the door locked. I cannot be certain it worked until he wakes.”

Sam tugged on his pants. Castiel handed him the key and Sam unlocked the metal cuffs that had held Dean, wincing when he saw the cuts and welts on his brother’s wrists and ankles. He felt anguish as he looked at Dean’s naked form on the examining table. “Can’t I move him somewhere more comfortable?”

“It’s too risky.” Castiel shook his head. Sam retrieved a blanket from the cabinet on the opposite side of the room.

Sam hesitated before covering his brother. “Shouldn’t we clean him?” Dean had his own cum on his stomach, and Castiel’s cum was smeared over his thighs and trickling out of his ass.

“I think we need to leave him be. Make sure the ritual has worked.” Castiel replied. He saw the shame and sorrow on Sam’s face. “He won’t remember.” He added more gently.

“He’ll ask.” Sam said, his eyes still on Dean. He placed the blanket over Dean.

“He’ll be ok.” Castiel said firmly. He placed a hand on Sam’s shoulder. Sam turned to look at Castiel. The angel looked so human and vulnerable now that his wings and grace were hidden again. He looked exhausted.

“Are you ok, Cas?” Sam asked softly. He forced himself to look into Castiel’s eyes. He felt his cheeks burning at the thought of the angel fucking his brother hard, and the fact he had been right there fucking Dean alongside of Castiel.

“Yes.” Castiel nodded. “Are you?”

Sam felt his eyes pooling with tears and an ache in the back of his throat. He didn’t trust himself to speak and only nodded. He took a shaky breath and swiped his eyes with one tattered sleeve.

“Go rest. I will take first watch.” Castiel murmured. He clapped Sam on the shoulder. “I will let you know as soon as he wakes.”

Sam nodded gratefully and left the room. Castiel heard the locks turning on the outside. He stood by Dean’s prone body and began the wait.

…

Sam had not meant to fall asleep when he went upstairs, even though Castiel had told him to rest. When he woke several hours later with a start, he could hear the murmur of voices next door. He flung off his sheets and stumbled toward Dean’s room. Dean was sitting on the bed, fully dressed, his hands on his knees. Castiel stood near the door.

“It worked, Sammy.” Dean said tiredly, scrubbing his face with one hand. “Castiel said I fought hard. I can’t seem to remember much after you started giving me the blood.”

Sam cleared his throat uncomfortably. “Yes. It worked. I’m glad you’re back, Dean.” He forced himself to walk over and sit beside his brother. Sam patted Dean’s shoulder awkwardly.

“Everything ok?” Dean looked directly at Sam. “Did I say or do something when I was darkside?”

Sam hesitated and Castiel answered for both of them. “No, Dean. That was the demon, Sam and I understand.” Sam nodded gratefully at Castiel.

“You look like shit, Sammy.” Dean said lightly.

Sam smiled tightly. “Speak for yourself.”

“You know, I could really use some food.” Dean suggested.

Sam jumped up at the chance to get out of the bunker. “I’m on it.” He looked at Cas. “So I’m just gonna go grab my brother cholesterol. And then I’m gonna get drunk.”  

Castiel raised an eyebrow but didn’t say anything. Sam put a hand on Castiel’s shoulder and left the room, not looking back at Dean when he said thanks. He felt sick and disgusted with himself but also relieved. Dean was back. But Sam would never ever tell him how they had brought him back. It was a secret that he would take to the grave. If Dean asked, Sam would just say Castiel had helped him finish the blood cure.

But he would never look at Dean the same again.


End file.
